Assigsob op one-half to f



(No' Model.)

T. J. OHRISTY... CRANK FOR OVERO OMING DEAD CENTERS.

No. 305,739. Patented Sept. 30,1884,

UNITED STATES PAThNT @rrrcn.

THOMAS J. CHRISTI, OF OLNEY, ILLINOIS, ASSIGNOR OF ONE-HALF TO F. T.

PHILLIPS, or

SAME PLACE.

CRANK FOR OVERCOIVHNG DEAD CENTERS.

SPECIFICATION forming part of Letters Patent No. 305,739, dated September 30, 1884.

Application filed December 27. 1883. (No modclil To to who/1t it may concern/.- V

Be it known that I, THOMAS J. CHRISTY, a resident of Olney, in the county of Richland,

' and the State of Illinois, have invented certain new and useful Improvements in Cranks; and I do hereby declare that the following is a full, clear, and exact description of the same, which will enable others skilled in the art to which it appertains to make and use the same, ref

erence being had to theaccompanying draw ings, which form a part of this specification, and in which- Figure 1 is a front view of my improved crank applied. Fig. 2 is a top view of the 1 same. Fig. 3 is a detailed view of the twoarmed crank; and Figs. 4, 5, and 6 are front views showing the crank and the arm in their different positions.

Similar letters of reference indicate correspending parts in all the figures.

My invention has relation to devices for converting reciprocating motion to rotary motion, or vice versa; and it consists in the improved construction and combination of parts of a crank having an arm attached to it, whereby the dead centers may be overcome, as hereinafter more fully described and claimed.

In the accompanying drawings, the letter A indicates the end of a shaft, which is pro- 0 vided with a two armed crank, 13, having its two arms, 0 and D, at right angles to each other. One of these arms, 0, is provided at its end with a wrist-pin, E, and the other arm has a laterally-projecting pin, F, at its end. 5 An arm, G, bent at an obtuse angle, is pivoted at one end upon the wrist-pin, has a slot, H, at its elbow, which slot slides upon pin F and has the pitman I hinged or pivoted to its other end in the usual manner. The slot in the elo bow of the pivoted arm forms a segment of a circle having its center in the center of the wrist-pin; and it will in this manner be seen that the arm may be rocked upon the wristpin, the slot sliding upon the projecting pin It will be seen 5 upon the other crank-arm.

that as the pitman is reciprocated it will act upon the outer end of the bent arm in the same manner as upon the end of a crank, revolving the arm and the crank and the shaft with it, and by referring to the drawings and supposing the crankshaft to revolve in the direction of the arrows upon the drawings it will be seen that in the moment when the end of the pitman and the outer end of thebent arm arrive at the dead-center at the farthest end of the stroke of the pitman the weight of the pitman and of the bent arm, together with the pushing force exerted by the pitinan, willdraw the end of the bent arm downward, the said arm sliding upon the pin, which will bring the outer end of the arm and of the pitman below the dead-center, allowing the pit-man to pull the arm around to the dead-ccnter at the inner end of the stroke of the pitinan, where the pull upon the pitman and consequently upon the arm will raise the end of the latter above the dead-center, allowing the pushing motion of the pitman to rotate the arm and cranks, as shown in Figs. 4, 5, and 6.

Having thus described my invention, I claim and desire to secure by Letters Patent of the United States- A The combination of a revolving shaft, a two armed crank secured upon the end of the shaft and having a Wristpin upon one arm and a laterally-projecting pin upon the other arm, an arm bent at an obtuse angle pivoted at one end upon thewrist-pin and sliding with a slot at its elbow upon the pin of the other arm, and a pitman pivoted or hinged at its end upon a pin at the outer end of the arm, as and for the purpose shown and set forth.

In testimony whereof I have hereunto set my hand this the 8th day of December, A. D. 1883.

THOMAS J. CHRISIY.

In presence of- GODFREY I-I. LASAR, OHARLns PIOKLES. 

